SubTree

public boolean isSubTree(TreeNode T1, TreeNode T2) {
        if (T2 == null) return true;
        if (T1 == null) return false;
        return (isSameTree(T1,T2) || isSubTree(T1.left, T2) || isSubTree(T1.right, T2));
    }
    public boolean isSameTree(TreeNode T1, TreeNode T2) {
        if (T1 == null && T2 == null)
            return true;
        if (T1 == null || T2 == null)
            return false;
        if (T1.val != T2.val)
            return false;
        return (isSameTree(T1.left, T2.left) && isSameTree(T1.right, T2.right));
    }